hofmann



APPLICATION FH ED 0018!, 1918.

Patented June 29, 1920.

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APPARATUS FOR DRYING'GOODS IN LAYERS.

APPLICATION FILED OCT. 3!. 191a.

Patented June 29,-1920.

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UNITED STATES ALFRED HOFMANN, or zUnIoH, SWITZERLAND. I

I APPARATUS FOR. DRYING Goons IN LAYERS.

Application filed October 31, 1918.- Serial No. 260,559;

To all whom it may concern:

Be it known that .I, ALFRED HorMANN, a citizen of the Republic ofSwitzerland, residing at 7 Asylstrasse, Zurich, in the Canton of Zurich,Republic of Switzerland,have invented certain new and usefulImprovements in Apparatus for Drying Goods in Layers; and I do herebydeclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains. to make and use the same, reference being. had to theaccompanying drawings, and to letters of reference marked thereon, whichform a part of this specification. 1

The usual known drying machines having a number of conveyer bands havethe draw- 7 back that only. one half, namely the upper half or stretchof the conveyer bands is utilized, while the lower half .or stretch runsidly. This entails a'double expenditure of constructional materials andpowerand also a greater height of the machines. A further drawback isthat a portion of the drying air can escape (with the loss of heat)almost without hindrance through theopen spaces left for the passage ofthe material being dried from an upper on to the next lowerv band. Heatis also lost by the large cooling surface of the machines due to theirheight.

This invention relates to the type of drying apparatus wherein anendlessconveyer' Now the object of my invention is to obviate the abovedescribed defect and to use practically the whole length of thedifferent runs of the conveyer for drying purposes.

According to this invention I employ means which effect tilting anddischarging of the frames at points beyond the centersv of the guideanddriving wheels for the conveyer. In using the practically whole lengthof the runs, the. drying air is more perfectly utilized.

Two constructional forms of the im ings in which proved drying apparatusare illustrated by way of example in theaccompanying draw- F gure 1 is avertical section on the line AB of Fig. 2.

Fig. 2 is a horizontal section on the line C-.-'D of Fig. 1 afterremoval of the carryng frames and their conveying and guid-- lI1(lQVlC6S. I *ig. 3 is a vertical cross section on the line EF of Fig. 1.f Fig. 4 shows heating pipes with mixing plates and roof-like hoods;

F 1g. 5 is a separate view of tipping frames at a left hand turningpoint.

Fig. 6 is a plan of Fig. 5. 1

; F ig. 7 isa separate view of tipping frames at a right hand turningpoint with the exception of the topone.

Fig. 8 shows the top turning point at the right hand by which framesthat face upward-in an upper stretch of the conveyer are also caused tofaceupward in the lower stretchof the conveyer.

Fig. 9 is a partial side elevation of Fig. 87 and J V PATENT oFFlcE.

Fig. 10 is a separate view of the means of tensioning the endlessconveyer chains.

. As shown the improveddrying apparatus comprises adrying chamber 1provided with bearings on its longer sides for the chain driving wheels2 and the chain guide wheels 3, and withpitch chains for both, taking aserpentine course through the drying chamber 1. Each shaft 5 of thechain driving wheels 2 carries outside the chamber 1 a worm wheel 6.With these gearing with worm wheels 6, there engage worms 8 fixed on acommon vertical shaft 7 A bevel wheel 9 (Fig.2) fixed on the shaft 7engages with a bevel wheel, 13 fixed on a shaft 12 that carries beltpulleys 10, 11. Shafts 1 1, 15

carrying two wheels 16, 17 outside the drying chamberl are mounted inangle-armed levers 19 fulcrumed on pins 18 (Figs. 1 and 10) and theirhorizontal arms are under the action of springs .20. This arrangementserves to tension the endless chains when they become expanded by heatand to allow the chains to contract'again in cooling.

The conveyer for the material to be dried consists of frames 21 pivotedon inwardly projecting portions of the joint pins 22 of the chains4::(Figs. 5 and 6), and capable of swinging between the chains. In thismovehand .portion). and Fig. 8, the frames 21 ment, as willbe perceivedfrom Fig. 1 (right with their projecting portions (borders) 23 inpassing from an upper stretch of the con tween the frames 21 widen onlygradually and therefore allow the material to drop only very graduallyso as not to form any heaps. The material lying on the flat side of theframes 21 is carried along by angle bars 24 (Fig. attached to theundersides of the frames. The material is prevented from fallingsidewise by the sides 25 of the drying chamber (Fig. 9).

The chains 4 slide along guides 26 between. which the frames have roomto swing. These guides 26 which are arranged in recesses in the sides 25of the drying chamber 1 and are interrupted at the turning points,

are bent down at one end and bent up at the other. Both ends of theguides are extended beyond the centers ofv the corresponding guide anddriving wheels, so that practically the whole length of the differentruns of the conveyer may be utilized for drying purposes. At their freeends the frames 21 carry at each side a shoe 27 or a roller 28,

adapted to run on the guides 26. hen the shoes 27 or the rollers 28 haverun off the downwardly bent ends of a pair of top bars 26 the framescomeinto a pendulating position (Figs. 5 and 7). until the shoes 27 orthe rollers 28 have run up again on to the upwardly bent ends of. a pairof lower bars 26, thereby completing the turning of the frames '21through 180.

As far as the top turning point (Fig. 1 right, andFig. 8) the frames 21are pulled by the chains 4, but from that point onward they are pusheduntil they pass out of the drying chamber. Consequently the firstturning point is constructed somewhat difq ferently from the otherturning points (Fig. 8). The chain pins 22 that carry the frames 4 movein advance of the latter so that these remain approximately in ahorizontal posi tion until their'rollers 28 haverun off the downwardlybent ends of the guides 26. Then they rock in the downward directionuntil the rollers 28 meet upwardly bent springs 29 that are carried bythe guides 26 and serve to moderate the impact of the frames. Thesprings 29 are bent downward and outward'at 30 for the purpose ofcausing a complete emptying of the frames 21 as they fall. 31 is a stopfor limiting the upward movement of the springs 29 Thus at this pointthe frames only change their direction", and instead of being pulledthey are henceforth pushed, but they are not turned through 180 as atthe other turning points. At all turning points however the upper framesare emptied on to the lower frames soas to turn and mix the material.For the purpose of supporting the material and allowing the air to passthrough, the frames are covered with perforated sheet metal or with wirecloth 32 as shown in Fig. 6.

On leaving thefdrying chamber 1 the frames. 21 lose their support andtilt down anddischarge their contents. By striking a pin 33 the frames21 are turned through 180 and completely emptied, and from this pointonward they are again pulled along by the chains 4.

In order toprevent the combustion gases employed to heat the material.from coming in contact with the drying air, the said gases as they le.ve the fireplace are first cooled by being ledthrough pipes 34, arrangedhorizontally underneath the drying chamber 1. By means of a damper thecombustion gases may also be led directly to the chimney- 36. and thenceinto the atmosphere; this is chiefly required. in the case of reatproduction of same on starting. TVhen the damper. 35 is closed thecombustion gases pass first through the pipes 34 that heat the dryingchamber, before they are led by a flue 37 into the chimney 36 where theyrise as far. as the closed damper 38, and'travel in opposite directionsthrough heating pipes 39. provided under the second, third. and fourthsections ofthat portion of the conveyer that is situated in the dryingchamber, to which they give up the larger quantity of their heat. Theypass then through a flue 40 into pipes 41 situated under the pipes 34,through which they travel in counter-current whereby the heat iscompletely utilized. A fan 42 draws the combustion gases out of thepipes 41 and delivers them into the atmosphere. In this manner thecombustion gases do, not come in. anyway in contact with the materialthat is being dried, and any sparks that may be carried over cannotignite the said material because even if the pipes, were leaky the fansuction would only such in drying air into the said pipes whereasburning particles could neverpass out.

The drying air. proper is blown by the fan 43 into the chamber 44 whichcontains the lowest heating pipes 41 where it takes up heat from thelowest/and coolest, section of those pipes so as to fully utilize theheat. It then flows along the highest and hottest pipes 34, the radiatedheat from which heats it to the permissible maximum temperature, andthen after having passed. throughthe iayers of material up to the upper.lengths of the piping it finally escapes into the atmos phere through anopening 45.

In passing from top to bottom through the layers of material, thedryingiair gives up heat to the material and becomes itself each of thethree heated layers. This greater heating causes also a more rapidevaporation since the greater part of the steam or vapor is taken up andcarried away by the hot air.

For the purpose of bringing the air into intimate contact with the pipes34 and 39 and mixing it uniformly, and also of providing free spaces toallow seeds and small particles to drop through without falling on tothe pipes and becoming burned, the said pipes are provided with mixingplates 46 and roof-like hoods 47 (Figs. 3 and 4). The droppings arecollected in the pit 44 under the heating apparatus whence they can beremoved from time to time through the opening 48.

What I claim is:

1. In an apparatus for drying bulk material a drying chamber, an endlessconveyer, leading in a sinuous form through the drying chamber, wheelsover which runs the conveyer, angle-armed levers situated outside thedrying chamber on pins, and springs acting on their horizontal arms,said wheels being supported by the bell-crank levers.

2. I11 an apparatus for drying bulk material, a plurality of heatingpipes arranged above one another for the purposeof progressively raisingthe temperature, roof-like hoods and mixing plates arranged over thepipes for utilizing the heating surface to the utmost, mixing the air,and preventing dropping particles of the material from falling on theaid heating devices.

3. A drying apparatus including in combination a drying chamber, anendless conveyer having a plurality of zig-zag runs, guide and drivingwheels and stationary guides over which the conveyer passes, framespivotally suspended from the conveyer, means to' effect tilting anddischarging of the frames at points beyond the centers of the guide anddriving wheel, pins positioned externally of the drying chamber, otheruide wheels over which the conveyer passes fastened on the pins,angle-armed levers on the pins, and springs acting on the horizontalarms of the bell crank levers.

4. A drying apparatus including in combination, a drying chamber, anendless conveyer having a plurality of zig-zag runs, guide and drivingwheels and stationary guides over which the conveyer passes, thedelivery end portions thereof being curved downward and extended beyondthe centers of the corresponding driving and guide wheels and thereceiving end portions being curved upwardly and extended beyond thecenters of the guide and driving wheels so as to reverse the directionof the frames and to invert the frame.

5. A drying apparatus including in combination, a drying chambertherein, an endless conveyer having a plurality of zig-zag runs, guideand driving wheels and stationary guides over which the conveyer passes,

conveyer frame pivotally suspended from the conveyer, means to effecttilting and discharging of the frame at points beyond the centers ofsaid driving and guide wheels,

pipes arranged horizontally under the drying chamber for receivingheating gases, heating pipes arranged in the drying chamber and inconnection with the horizontally disposed pipes, other pipes situatedbeneath the horizontal-pipes in connection with the heating pipes in thedrying chamber and a fan in connection with the last mentioned pipe andadapted to draw the combustion gases out of all of the said pipes.

6. A drying apparatus including in combination a drying chamber, anendless conveyer having a plurality of zig-zag runs, guide and drivingwheels and stationary guides over which the conveyer passes, framespivotally suspended from the conveyer, means to effect tilting anddischarging of the frames at points beyond the center of, the said guideand driving wheels, pipes arranged horizontally under the drying chamberadapted to receive heating gases, heating pipes arranged in the dryingchamber and in connection with the horizontally disposed pipes, otherpipes situated over the horizontally disposed pipes and'in connectionwith the heating pipe and drying chamber and roof, like hoods and mixingplates arranged over the first named pipe and over'the heating pipes inthe drying chamber for utilizing the heating surface to the utmost endfor mixing the air and preventing material from dropping and filling onthe heating pipes.

7. A drying apparatus, including in com bination, a drying chamber,driving wheels at one end of the chamber, guide wheels at the other endof the chamber, stationary guides between the wheels, an endlessconveyer operating over the wheels and guides so as to have a pluralityof zig-zag runs within the chamber, spring tensioned anglearmed leverspivotally mounted exteriorly of the chamber, guide wheels mounted on thepivots of the levers and over which the conveyer passes, conveyer framespivotally suspended from the conveyer, and means to effect tilting anddischarging of the frames at points beyond the centers of the firstmentioned guide and driving wheels.

In testimony whereof, I have signed my name to this specification.

ALFRED HOFMANN.

